Microsoft server 2008/2012 Filestore cals?

Hi all,
I'm wanting to build a filestore to replace an old linux box. am I correcting in thinking with server 2008/2012 you need a Cal per device that will access the server (this will be a pure file server) because if so this makes the cost of the box and storage jump from about £400 to about £3500

User based CAL:
With the User CAL, you purchase a CAL for every user who accesses the server to use services such as file storage or printing, regardless of the number of devices they use for that access. Purchasing a User CAL might make more sense if your company employees need to have roaming access to the corporate network using multiple devices, or from unknown devices, or simply have more devices than users in your organization.

Device based CALs

With a Device CAL, you purchase a CAL for every device that accesses your server, regardless of the number of users who use that device to access the server. Device CALs may make more economic and administrative sense if your company has workers who share devices, for example, on different work shifts.

External Connectors

If you want external users—such as business partners, external contractors, or customers—to be able to access your network, you have two licensing options:
Acquire CALs for each of your external users.
Acquire External Connector (EC) licenses for each server that will be accessed by your external users.

So now based on the above details you can justify yourself which one will be the most economically fit in your organisation.

if users are working from office only then the user based CAL will not be useful and in that case you have to go for Device based CAL.

Also note there are some processor/core based license. So make sure before purchasing CAL you have confirmed everything.